1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal module for a liquid crystal display that can minimize noise due to structural friction.
2. Description of the Related Art
A cathode ray tube (CRT) is a type of display generally used as a monitor. For example, a CRT can be used in a television, a meter, an information terminal or the like. However, the weight of a CRT can not be reduced to be light and the profile can not be reduced to be thin because of the use of a bulky electron gun that has to be in a glass tube.
A liquid crystal display (LCD) is replacing the CRT because an LCD has the advantages of a slim profile, light weight and low power consumption has been actively developed. The development of the LCD has recently progressed to such a degree that it can sufficiently perform a role as a flat panel display. As a result, LCDs are being used as monitors in laptop computers, desktop computers, outdoor large-sized screens above 30 inches, and flat panel wall-mounted TVs. The demand for such products continues to increase.
An LCD is a light-receiving device that displays an image by controlling an amount of light transmitted from one side to the other side of the LCD. Thus, the LCD needs a separate light source, such as a backlight assembly, to project light onto one side of a liquid crystal panel of an LCD such that an image can be displayed on the other side of the liquid crystal panel.
Backlight assemblies are generally classified into an edge type and a direct type according to the position of the light source with respect to a display surface. The direct type backlight assembly provides light in a direct path to the liquid crystal panel and an edge type backlight assembly provides light in an indirect path with a light guide plate to the liquid crystal panel. The direct type backlight assembly has the advantages of high light usage efficiency as well as easy attachment to a liquid crystal panel. In addition, the direct type backlight assembly and can be used with a liquid crystal panel of any size. A direct type backlight assembly is widely used in large-sized LCDs having a size greater than 30 inches.
The direct type backlight assembly does not need a light guide plate for converting light of a lamp at the edge of a liquid crystal panel into a surface light like an edge type backlight assembly. Instead, the direct type backlight assembly includes a plurality of lamps disposed below the display surface of the liquid crystal panel. Further, the direct type backlight assembly also includes a reflection sheet for reflecting light from the lamps toward the display surface to efficiently use all of the light from the lamps and a diffuser plate for scattering light so as to uniformly distribute light across the display surface of the liquid crystal panel.
FIG. 1 is a perspective view of an edge of a liquid crystal module employing a direct type backlight assembly according to the related art. More particularly, FIG. 1 shows the edge of a liquid crystal module before a guide panel is attached. FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1 and includes a guide panel.
Referring to FIGS. 1 and 2, the related art liquid crystal module includes a support side 12 for receiving and affixing ends of a plurality of lamps 10, a diffuser plate 14 with a side in contact with an upper surface of the support side 12, and a guide panel 18 affixing the diffuser plate 14 to the support side 12. A liquid crystal panel (not shown) is disposed on the diffuser plate 14 when the liquid crystal module is in use.
A reflection sheet 16 for reflecting the light projected by the lamps 10 toward a liquid crystal panel (not shown) is disposed below the lamps 10. Further, a plurality of optical sheets (not shown) may be inserted between the diffuser plate 14 and the liquid crystal panel (not shown).
The guide panel 18 and the support side 12 are coupled to each other by a coupling means, such as a bolt 19 or the like. Thus, the diffuser plate 14 is affixed to the support side 12. A continuous face of the support side 12 contacts the diffuser plate 14 at an area “A”. However, the related art liquid crystal module has a drawback in that its components expand and move due to changes in temperature. This expansion or movement can cause noise because of friction between the components.
When a power is applied to the liquid crystal module or an applied power is turned off, heat is generated or cooling begins, thereby causing the components to expand or contract. However, some of the components expand faster than other components and some of the components contract slower than other components. Thus, movement occurs between adjacent components having different rates of expansion or contraction. If there is a friction between components having different rates of expansion or contraction, a frictional noise can occur.
For example, when a power is applied to the liquid crystal module shown in FIGS. 1 and 2, the diffuser plate 14 is expands due to the increased temperature, so that a movement can occur in a direction toward the support side 12 in, for example, an X-axis direction across the upper surface of the support side 12. Since the guide panel 18 is affixed by the bolt 19, a force is applied down onto the diffuser plate 14 by the bolt 19 such that diffuser plate applies a force down, for example, in a Z-axis direction onto the support side 12. Thus, a noise is generated due to friction between the diffuser plate 14 and the support side 12 when the diffuser plate 14 expands.
FIG. 3 is a perspective view of the top and side surfaces of the support side shown in FIGS. 1 and 2. As shown in FIG. 3, the support side 12 according to the related art has a top surface in which a portion “A” contacts the diffuser plate 14 in a continuous strip. A frictional noise is generated because the diffuser plate 14 is held down against the support side 12 across the entire surface of the continuous strip of portion “A” when the diffuser plate 14 moves with respect to the support side 12 due to expansion or contraction of the diffuser plate 14 resulting from temperature changes.